C. Self Heating
Coal has a property to heat itself by reacting with oxygen in
air (oxidation), during oxidation it generate heater. In enclosed
situation, such as stowed in cargo holds, the generated heater
has little way to radiation, it will cause the temperature of coal
rise, high temperature will accelerate the oxidation, and
generate more heater㸪vice versa. Oxidation is stimulated by
the accumulation of heat and cause the coal's own temperature
rapidly rises, some time the temperature may reach its selfignite
point, so it pose the coal with a potential risk of fire. The
self-ignite temperature varies with the qualities of coal, is
generally range from 250Υ to 350Υ. The following facts are
regarded as simulative to self heating: the lower degree of
coalification, the more oxidation and easy to be self heating or
self ignition; the temperatures inside the cargo hold and nearby
seawater; condition of coal itself when loaded aboard; duration
of transit; suitable moisture content, which stimulates oxidation
of coal and facilitates self heating. But if too much adherent
water on stored coal, air between coal pieces is driven away,
and therefore the oxidation of coal will be suppressed to
prevent self heating, also less adherent water on stored coal
will retard the oxidation.